To provide a cooling tower capable of discharging the impurities and scale separated out/dropped in a pipe conduit in introducing the activated water to the external with the overflow water, and reducing the labor hour for maintenance.

A water activating means 60 is mounted on a circulating passage and the like, a discharged water guide part 15 is mounted outside of an overflow pipe 14, and the water is allowed to reach an upper end opening of the overflow pipe 14 from a lower part to an upper part between the discharged water guide part 15 and the overflow pipe 14, when a water level of a lower tank 10 is over an upper end position of the overflow pipe 14, so that sediments accumulated on a bottom of the lower tank 10 is raised and discharged to the external through the overflow pipe 14 in accompany with the water. The impurities and scale separated out and dropped in the circulating passage by cleaning performance of the activated water, reach the lower tank 10, are accumulated there, and then efficiently discharged every overflowing of the water, whereby the labor hour and the cost of the maintenance for removing the sediments and the like can be reduced.